Matrix switch with improved flexible insulative spacer arrangement

ABSTRACT

A matrix switch comprises an orthagonal arrangement of two sets of parallel conductors spaced from one another by a plurality of resilient elements. Preferably, the switch is made by securing together two one-sided flat conductor cables, each of which comprises a plurality of alternating, parallel conductors and elastomeric elements, with the heights of said elastomeric elements being greater than the heights of said conductors. Each cross-over point of the spaced conductors forms a switch point which is activated upon depression of the upper conductor into contact with the lower conductor. The orthogonally disposed flat conductor cables are held in a suitable housing including printed circuit board pads to which the conductors are connected, thereby facilitating simultaneous connection of the conductors to conventional multi-pin printed circuit board connectors for connection to the electronics used in conjunction with the matrix switch.

United States Patent 1 51 3,668,337 Sinclair 1 June 6, 1972 1541 MATRIXSWITCH WITH IMPROVED 3,111,721 11/1963 Montague, Jr. ..200/86.5 x

FLEXIBLE INSULATIVE SPACER P Ex J R s u nmary ammerco ARRANGEMENTAttorney-David Teschner [72] Inventor: William Y. Sinclair, Frenchtown,NJ. [73] Assignee: Thomas 8: Betts Corporation, Elizabeth, [57] A CT NJ.A matrix switch comprises an orthagonal arrangement of two sets ofparallel conductors spaced from one another by a plu- Filed: v 1971rality of resilient elements. Preferably, the switch is-made by [21 1APPL No: 107,192 securing together two one-sided flat conductor cables,each of which comprises a plurality of alternating, parallel conductorsand elastomeric elements,'with the heights of said elastomeric [52] US.Cl. ..200/5 A,200/86 R, ZOO/86.5, elements being greater than theheights of said conductors. 200/ 1 59 B Each cross-over point of thespaced conductors forms a switch [51 Int. Cl ..IIOlh 9/26, H0111 13/26 pint whi h i activated p n pre i of h pper on uc- [53] Field f Searchgoo/5 R 5 A, 8 A, 865 159 B tor into contact with the lower conductor.The orthogonally disposed flat conductor cables are held in a suitablehousing [56] References Cited including printed circuit board pads-towhich the conductors are connected, thereby facilitating simultaneousconnection UNITED STATES PATENTS of the conductors to conventionalmulti-pin printed circuit board connectors for connection to theelectronics used in 3,35 l ,724 l 1/1967 Goble ..200/86 R conjunctionwith the matrix switdh 3,308,253 3/1967 Krakinowski 200/86 R X 3,584,1626/1971 Krakinowski ..200/5 A 12 Claims, 9 Drawing Figures I j myzwmareaPATENTEUJUR 6 I972 sugar 2 or 2 FIG.7

mvsmon. Mu/AM K Swcm/R MATRIX SWITCH WITH IMPROVED FLEXIBLE INSULATIVESPACER ARRANGEMENT The present invention relates to a matrix switch, andmore particularly a non-coded electromechanical keyboard switch.

To furnish low cost, high reliability keyboard switches to the rapidlygrowing computer and information handling equipment industries, switchmanufactures are offering an array of units in a wide range of sizeswith a large number of options. One commonly available keyboard switchemploys a plurality of reed switches arranged in keyboard fashion in asuitable housing. Each reed switch consists of two plated reeds or steelblades cantilevered from each end of a sealed glass tube, eitherevacuated or inert gas filled. Mercury wetted reed switches use smallquantities of mercury to help make contact and reduce bounce. Permanentmagnets, positioned on a movable plunger, cause a reed switch to open orclose. Although reed switches have had a history of successful switchingapplications, the cost of the individual reed switches, and themanufacturing cost of making the relatively complicated precision reedswitches has mitigated against their use in applications requiring arelatively inexpensive matrix switch. In addition, because of the numberof different components embodied in a reed switch, the latter isrelatively delicate and complex in construction.

A second commonly available matrix switch of the electromechanical typeemploys semi-conductor devices. As in the cases of reed'switches, matrixor keyboard switches made with semi-conductor devices are expensive tomanufacture and accordingly the cost of such a switchis prohibitive forcertain applications.

The subject invention provides a matrix switch which is simple inconstruction, simple in operation and has a high switch density persquare inch of planar surface. In addition, the subject matrix switchprovides a low cost matrix switch which is an electromechanical switchcapable of being housed in a suitable housing having means forinterconnection to printed circuit board connectors in order to effectrapid connection and disconnection of a plurality of conductors.

Briefly, the present invention is made by securing together,

in orthogonal relationship, two one-sided flat conductor cables, each ofwhich comprises a plurality of parallel conductors alternating with aplurality of elastomeric strips. The cross-section of each elastomericstrip is greater than the cross-section of the adjacent conductorswhereby, with the two one-sided flat conductor cables in abuttingrelationship at right angles, and with the conductors disposed inopposed relationship, the crossed elastomeric elements maintain apredetermined spacing between the conductors. An electrical connectionat a cross-over point of two respective electrical conductors isestablished by merely depressing one point in the upper one-sided flatconductor cable so as to cause depression of the upper conductor andcompression of the adjacent elastomeric members to establish electricalcontact between said respective conductors. When the applied force isremoved, the elastomeric members return the composite structure to itsinitial configuration. Each one-sided flat conductor cable is mounted inone part of a two-part housing, each part of the housing includingconventional printed circuit board pads for connection to theconductors. The pads are arranged to facilitate connection to amulti-contact connector of the type generally known to the industry.

The objects of the invention will become more apparent from thefollowing description and appended claims, taken in conjunction with thefollowing drawings:

FIG. 1 illustrates a one-sided flat conductor cable forming a portion ofthe matrix switch of the subject invention;

FIG. 2 is a sectional view taken along lines 2-2 of FIG. 1;

FIG. 3 illustrates a perspective view of the connection of a one-sidedflat conductor cable mounted in one-half of a housing for the subjectmatrix switch;

FIG. 4 illustrates a perspective exploded view of the components forminga preferred embodiment of the matrix switch of the subject invention;

FIG. 5 illustrates a partial sectional view of a cross-section of theassembled matrix switch, indicating at one point the position of theelements of the matrix switch during the formation of a switch contactbetween conductive elements of the one-sided cables of the matrixswitch;

FIG. 6 illustrates a perspective view of a keyboard cover to be employedin conjunction with the subject matrix switch;

FIG. 7 illustrates a cross-section taken along lines 7-7 of FIG. 6, andillustrating a partial cross-sectional view of a button contact forminga portion of the keyboard cover; I

FIG. 8 illustrates a partial sectional view of a cross-section of amodified form of matrix switch, and

FIG. 9 illustrates a partial sectional view of a cross-section ofanother modified form of matrix switch.

Turning to FIG. 1, there is illustrated a one-sided flat conductor cable1 forming a portion of the subject matrix switch. Flat conductor cable 1comprises a sheet of insulation material 2 having bonded thereto analternating arrangement of parallel elongated elastomeric elements 4 andelongated conductors 3. As illustrated in FIG. 2, the cross-sectionalarea of each elastomeric element 4 is greater than the adjacentelectrical conductors 3. For certain applications the cross-sectionalarea of a conductor 3 may be greater than the area of the elastomericelement 4, however in all instances it is necessary that the height orvertical dimension of the elastomeric elements 4 be greater than theconductors 3. The elastomeric elements 4 may be made of any suitablenon-electrically conducting element such as silicone or nylon.Preferably, each element 4. has a high degree of plastic memory so as toreturn to its original configuration after being deformed. Conductors 3are illustrated as being rectangular in cross-section, although it isreadily apparent that conductors 3 may be conventional round wires.

As illustrated in the perspective view of FIG. 1, the conductors 3extend beyond the longitudinal limits of the sheet material 2 forconnection to circuit pads disposed on each half of the housing of thematrix switch, to be described below.

FIG. 3 illustrates the lower half of the housing as comprising a planarstructure 5 made of generally rigid, non-electrically conductivematerial, e.g., plastic, having two parallel side rails 6 so as todefine a slot or central recessed portion R for the mounting ofone-sided cable 1. Apertures 7 are formed in the comers of the structure5 for the reception of suitable fastening means to hold the two halvesof the housing together. The recess R formed in each structure 5 isslightly longer than the length of the cable I, and suitable printedcircuit pads 8 are fonned at the opposite ends of the recess R inalignment with the conductors 3 of the cable 1. With the conductors 3electrically connected to pads 8, it is readily apparent that theconductors 3 of the one-sided cable may be rapidly and simultaneouslyconnected to the contacts of'a conventional multi-pin connector (notshown) commonly used in the printed circuit board art thereby enablingrapid connection of the conductors 3 to the electronics system to whichthe matrix switch is to be connected. The heights of the side rails 6above the base of the recess R formed in structure 5 are sufficient toenable connection of the multi-pin connector to the structure 5.

The upper structure 5' (see FIG. 4) is generally similar to thestructure 5 illustrated in FIG. 3 except that the portion of the recessR defined between the side rails 6 and edge portions of structure 5'wherein the pads 8' are connected is omitted. Accordingly, the upperstructure 5' comprises a generally square or rectangular frame definedby side rails 6, 6" and the edge portions extending therebetween. Bythis arrangement, when the housing (consisting of structures 5 and 5')is fully assembled, a compressive force may be directly applied to theupper one-sided flat cable assembly and to a point of cross-over of theconductors to establish an electrical contact between the respectiveconductors. If desired, the area defined by said frame may be defined bya flexible membrane or the like which would readily deform upon theapplication of a concentrated vertical force.

The connection of the conductors to the pads of the upper structure 5 isidentical to that described with respect to the lower structure 5.

Turning to FIG. 4, after the one-sided cables are connected to therespective halves of the housing, the respective structures 5 and 5' areassembled so that the longitudinal axes of the cables 1, l are disposedangularly relative to one another, the conductors are in facingrelationship, and the elastomeric elements are abutting. The aperturesin the comers of the respective side rails 6 and 6 of the structures 5and 5' are aligned for passage of suitable bolting means to hold thestructures 5, 5 together. As illustrated in FIG. 5, the conductorsextend at right angles to one another thereby defining discretecross-over points. As may be readily appreciated, it is merely necessaryto apply a concentrated force at one of the intersections or cross-overpoints of the conductors of the respective cables in order to form anelectrical connection between the conductors 3 and 3 of the upper andlower cables.

FIG. 5 illustrates in partial sectional view the establishment of anelectrical connection between a conductor of the upper one-sided flatconductor cable and a conductor of the lower one-sided flat conductorcable. As illustrated, the application of a concentrated force causesthe upper conductor to deflect a sufficient amount to form an electricalconnection to the lower conductor. At such time, the resilientelastomeric elements in the immediate vicinity of the force aredistorted thereby effectively aiding in the deflection of the upperconductor. Also, at such time, the lower structure 5 effectivelyprovides a rigid base below the matrix switch assembly.

In order to facilitate the formation of an electrical connection betweenconductors of one cable 1 with the other cable, a suitable keyboardswitch arrangement, such as illustrated in FIG. 6 may be provided. Asshown in FIG. 6, the keyboard cover 10 comprises a molded plastic memberincluding a plurality of button contacts 11 arranged to coincide withthe points of intersection of the cables. Suitable apertures 12 areprovided in cover 10 to enable connection to the housing 5,

' 5'. As shown in FIG. 7, each button 11 includes a rounded upperportion 13 on which is formed suitable indicia, while the lower portionthereof consists of a depending stem 14. As may readily be appreciated,the molded plastic cover 10 is sufficiently flexible to enabledepression of the buttons 11 in order to force a conductor of the upperone-sided flat conductor cable 1 against a conductor of the lower cable1, without causing disturbance of adjacent conductors.

While a preferred embodiment of the subject matrix switch has beendescribed and illustrated, it is readily apparent that otherconfigurations and modifications of the subject matrix switch may bereadily designed in order to satisfy particular requirements for thespecific applications for which the matrix switch is intended. Forexample, the upper and lower onesided flat conductor cables need not bedisposed at right angles, and for a certain application it may bedisposed at angles less than 90. Similarly, instead of using a housingcomprising two parts, it is readily apparent that a lower rigid housingmay be employed for accommodating one one-sided flat conductor cable,and the other one-sided flat conductor cable may be positioned angularlywith respect to the first one-sided flat conductor cable and alsomounted on said rigid housing, thereby also defining a matrix switchincluding a plurality of cross-over intersections. In like manner thecross-section configurations of the elastomeric members may takeconfigurations other than round, such as triangular or square, as longas the cross-sectional configuration does not interfere-with thedisplacement of the upper conductor as it is forced in contact with thelower conductor.

Another possible modification of the subject matrix switch, asillustrated in FIG. 8 or FIG. 9, is the provision of employing only oneflat conductor cable having an alternating arrangement of conductors andenlarged elastomeric members, while the other cable merely consists of aconventional one-sided cable comprising a plurality of conductors bondedto a sheet of insulating material. In such case, the spacing betweenconductors of the two cables would be maintained merely by theelastomeric elements secured to one cable. The remainder of the matrixswitch would be similar to that illustrated and described. 5 FIG. 8illustrates the modification just described where the upper element 5'employs a flat conductor cable having an alternating arrangmeent ofconductors 3' and enlarged elastomeric members 4 bonded to the web orsheet 2, while the other cable, mounted on the lower element 5 of thematrix switch, merely consists of a conventional one sided cablecomprising a plurality of conductors such as the conductor 3 bonded tothe sheet 2 of insulating material.

FIG. 9 shows such a modification in which the lower element 5 of thematrix switch employs a flat conductor cable having an alternatingarrangement of conductors such as the conductor 3 and enlargedelastomeric members such as the member 4, whereas the upper element 5merely has a conventional one sided cable comprising a plurality ofconductors such as the conductor 3' bonded to the flexible carrier sheet2' which, of course, is made of insulating material. As in the case ofFIG. 5, the application of concentrated force to make a contact at acrossover of a conductor of the upper element and a conductor of thebottom element is shown in FIGS. 8 and 9, the force being indicated byan arrow in the same manner as in FIG. 5.

Having thus described the invention it is not intended that it be solimited, as changes may be made herein without departing from the scopeof the invention. Accordingly, it is intended that the foregoingAbstract of the Disclosure and the subject matter described above and asshown in the drawings be interpreted as illustrative only, and not in alimiting sense.

What is claimed is:

l. A matrix switch comprising:

a first one-sided flat conductor cable including an alternatingarrangement of parallel elongated conductors and elongated,non-electrically conductive resilient members bonded to a sheet ofresilient insulation material, the height of said resilient membersbeing greater than the height of said conductors;

a second one-sided flat conductor cable including an alternatingarrangement of parallel elongated conductors and elongated,non-electrically conductive resilient members bonded to a sheet ofresilient insulation material, the

height of said resilient members being greater than the height of saidconductor;

said first and second one-sided flat cables being secured together insuch manner that the respective resilient members are in abuttingengagement and extend angularly relative to one another thereby defininga plurality of cross-over points between the respective conductors ofsaid first and second flat conductor cables.

2. A matrix switch as in claim 1 wherein the elongated conductors andresilient members of said first one-sided flat conductor cable aredisposed perpendicular to the elongated conductors and elongatedresilient members of said second onesided fiat conductor cable.

3. A matrix switch as in claim 1 wherein said resilient members compriseelastomeric members having a circular crosssection.

4. A matrix switch as in claim 1 wherein each one-sided fiat conductorcable is secured to one-half of a housing assembly, which housingassembly includes electrically conductive pads to which the conductorsof said flat conductor cables are electrically connected.

5. A matrix switch as in claim 4 wherein a flexible keyboard cover isprovided to enclose said housing, which keyboard cover includesdepressible keys aligned with the cross-over points of the conductors ofsaid first and second flat conductor cables.

6. A matrix switch comprising:

a first member including a plurality of generally parallel elongatedelectrical conductors bonded to a sheet of flexible insulation material;

a second member including an alternating arrangement of generallyparallel elongated electrical conductors and elongated, non-electricallyconductive resilient members bonded to a sheet of flexible insulationmaterial, the height of said resilient members being greater than theheight of said conductors;

said first and second members being secured together in such manner thatthe resilient members of said second member engage the conductors ofsaid first member and extend angularly relative thereto, therebydefining a plurality of cross-over points between the conductors of saidfirst and second members 7. A matrix switch as in claim 6 wherein theconductors of said first and second members are disposed perpendicularto each other.

8. A matrix switch as in claim 6 wherein the resilient members of saidsecond member comprise elastomeric members having circularcross-sections.

9. A matrix switch as in claim 6 wherein said first and second membersare disposed in a flexible housing assembly I 6 including electricallyconductive pads to which the respective conductors of said first andsecond members are electrically connected.

10. A matrix switch as in claim 9 wherein a flexible keyboard cover isprovided to enclose said housing, which keyboard cover includesdepressible keys aligned with the cross-over points of the conductors ofsaid first and second members.

11. A matrix switch .as in claim 1 wherein said resilient memberscomprise an elastomeric member having a triangular,

cross-section.

12. A matrix switch as in claim 1 wherein each one-sided flat conductorcable is secured to one-half of a housing assembly, which housingassembly includes electrically conductive paths to which the conductorsof said flat conductor cables are electrically connected and whereineach half of said housing assembly comprises a planar surface havinglongitudinally extending side rails, with the flat conductor cabledisposed on the planar surface position between said side rails.

1. A matrix switch comprising: a first one-sided flat conductor cableincluding an alternating arrangement of parallel elongated conductorsand elongated, non-electrically conductive resilient members bonded to asheet of resilient insulation material, the height of said resilientmembers being greater than the height of said conductors; a secondone-sided flat conductor cable including an alternating arrangement ofparallel elongated conductors and elongated, non-electrically conductiveresilient members bonded to a sheet of resilient insulation material,the height of said resilient members being greater than the height ofsaid conductor; said first and second one-sided flat cables beingsecured together in such manner that the respective resilient membersare in abutting engagement and extend angularly relative to one anotherthereby defining a plurality of cross-over points between the respectiveconductors of said first and second flat conductor cables.
 2. A matrixswitch as in claim 1 wherein the elongated conductors and resilientmembers of said first one-sided flat conductor cable are disposedperpendicular to the elongated conductors and elongated resilientmembers of said second one-sided flat conductor cable.
 3. A matrixswitch as in claim 1 wherein said resilient members comprise elastomericmembers having a circular cross-section.
 4. A matrix switch as in claim1 wherein each one-sided flat conductor cable is secured to one-half ofa housing assembly, which housing assembly includes electricallyconductive pads to which the conductors of said flat conductor cablesare electrically connected.
 5. A matrix switch as in claim 4 wherein aflexible keyboard cover is provided to enclose said housing, whichkeyboard cover includes depressible keys aligned with the cross-overpoints of the conductors of said first and second flat conductor cables.6. A matrix switch comprising: a first member including a plurality ofgenerally parallel elongated electrical conductors bonded to a sheet offlexible insulation material; a second member including an alternatingarrangement of generally parallel elongated electrical conductors andelongated, non-electrically conductive resilient members bonded to asheet of flexible insulation material, the height of said resilientmembers being greater than the height of said conductors; said first andsecond members being secured together in such manner that the resilientmembers of said second member engage the conductors of said first memberand extend angularly relative thereto, thereby defining a plurality ofcross-over points between the conductors of said first and secondmembers.
 7. A matrix switch as in claim 6 wherein the conductors of saidfirst and second members are disposed perpendicular to each other.
 8. Amatrix switch as in claim 6 wherein the resilient members of said secondmember comprise elastomeric members having circular cross-sections.
 9. Amatrix switch as in claim 6 wherein said first and second members aredisposed in a flexible housing assembly including electricallyconductive pads to which the respective conductors of said first andsecond members are electrically connected.
 10. A matrix switch as inclaim 9 wherein a flexible keyboard cover is provided to enclose saidhousing, which keyboard cover includes depressible keys aligned with thecross-over points of the conductors of said first and second members.11. A matrix switch as in claim 1 wherein said resilient memberscomprise an elastomeric member having a triangular cross-section.
 12. Amatrix switch as in claim 1 wherein each one-sided flat conductor cableis secured to one-half of a housing assembly, which housing assemblyincludes Electrically conductive paths to which the conductors of saidflat conductor cables are electrically connected and wherein each halfof said housing assembly comprises a planar surface havinglongitudinally extending side rails, with the flat conductor cabledisposed on the planar surface position between said side rails.